In ice age 3, we are introduced to the crazy weasel Buck. One of the most defining things about him (other than his eyepatch) is his knife (he got both at the same time). Here is a still of him with it:

Later, in Ice age 4, we see Gupta, one of Gutt's crew give Weiner his knife:

2 Answers
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I think the resemblance is just that. They probably just couldn't be bothered to make another original "rugged knife" model for the movie, so they just used Buck's Knife model instead. Maybe it was a placeholder for until they made another knife, but they accidentally left it in.